The present invention relates to a gas turbine engine combustion chamber having strategically placed dilution orifices to optimize the mixture of gases burned in the combustion chamber.
Annular combustion chambers for gas turbine engines are well known in the art and typically comprise inner and outer walls joined at one end by an end wall to bound the combustion chamber, which has an outlet opening at an end opposite the end wall. A plurality of fuel injectors are arrayed through the end wall, each fuel injector having an air injection swirler to induce vortices in the fuel/air mixture around the injector axis. Typically, the interior of the combustion chamber is divided into a combustion zone extending in a downstream direction from the end wall which blends into a dilution zone in which dilution air is introduced through orifices in the inner and/or outer walls to dilute the combustion gases and the reduce their temperatures so that they are compatible with the turbine located downstream of the combustion chamber outlet.
The combustion chamber walls of an aeronautical gas turbine engine have many air intake orifices to facilitate the burning of the fuel injected into the combustion chamber. The orifices may be divided into air intake orifices which supply the major portion of the air to support the combustion in the combustion zone of the chamber, and dilution orifices located further downstream from the end wall in the dilution zone to supply air to the burned gases so as reduce the temperature of the burned gases so as to be compatible with the thermal strength of the turbine.
The combustion of the fuel/air mixture takes place in the combustion zone of the chamber in which primary oxidizer is supplied through the injection swirlers and through various air inlet orifices in the end wall of the combustion chamber.
The dilution orifices are located in rows of planes transverse to the axis of the combustion chamber and, typically, the orifices in the outer annular wall are circumferentially aligned with orifices in the inner annular wall. A first row of such orifices, often called the "primary orifices" is located at the juncture of the combustion zone and the pollution zone. Part of the air introduced through these "primary orifices" circulates toward the combustion zone and takes part in the combustion of the fuel/air mixture, while another portion of the air enters the dilution zone and contributes to the dilution of the burned gases. The first row of orifices may be followed in a downstream direction by one or more rows of dilution orifices which introduce air into the dilution zone.
The mutually opposite location of the primary orifices and dilution orifices in the inner and outer walls produces an obstacle to the burned gases coming from the combustion zone which adversely affects the homogenzing of the temperatures of the burned gases fed to the turbine. This deleteriously affects the efficient operation of the turbine.